spherical, membraneous organelles which contain activated digestive enzymes. If these enzymes are released into the cytoplasm, they cause the cell to self-digest
first subphase of interphase characterized by vigorous growth and metabolism
Final phase of mitosis.
1) A cell is the basic structural and functional unit of living organisms.
2) Activity of an organism depends on both the individual and collective activities of its cells.
3) Biochemical activities of cells are dictated by their shapes and forms.
4) Continuity of life from one generation to another has a cellular basis.
intracellular fluid containing organelles
Second phase of mitosis or meiosis in which the duplicated chromosomes line up along the equatorial plate of the spindle.
the third stage in mitosis or meiosis following metaphase in which the daughter chromosomes move away from each other to opposite ends of the cell.
first stage of mitosis or meiosis in eukaryotic cell division, during which the nuclear envelope breaks down and strands of chromatin form into chromosome
In RNA transcription, what replaces thymine in DNA, to make it slightly different?
Passive forms of diffusion
Osmosis and simple diffusion
carrier assisted diffusion
a type of facilitated diffusion that involves the binding of a substrate to a carrier causing a change in the carrier. Carriers can change shape and assist big molecules through the cell wall.
principle site of ATP synthesis aka the "powerhouse of the cell"; contain DNA, RNA and ribosomes
site of protein synthesis
Cell organelle that acts as a packaging warehouse for protein.
A membrane junction that acts as a spot weld anchoring cells together.
types of proteins found in a plasma membrane
1) Integral, 2) Peripheral
types of junctions found in plasma membrane
1) gap junctions
3) tight junctions
Transmembrane proteins that form specific channels, or PORES, in a cell membrane that allow only water to move freely in single file diffusion through the wall.
Forms of Passive Transport
2) Simple Diffusion
3) Carrier facilitated transport
4) Channel mediated transport
Tendency of molecules or ions to move from an area where they are in higher concentration to an area where they are in lower concentration.
Active Cell Process
Cell requires ATP (metabolic energy) to move substances across the cell membrane
The tendency of water to move into the cell by osmosis.
Back pressure exerted by water against the membrane.
contain a lower concentration of nonpenetrating solutes
structural unit of all living things
a communicating junction between adjacent cells; present in electrically excitable tissues such as the heart and smooth muscle
thin linker protein filaments that extend from plaques and fit together like teeth of a zipper in the intercellular space
type of membrane junction that is a series of integral protein molecules in the plasma membranes of adjacent cells fuse together, forming an impermeable junction that encircles the cell
membrane protein functions
2) Receptors for signal transduction
3) Attachment to cytoskeleton and extracellular matrix
4) Enzymatic Activity
5) Intercellular joining
6) Cell-cell communication
fuzzy, sticky carb rich area at cell surface; sugar covered proteins
20% of cell membrane surface; concentrating platforms for certain receptor molecules; dynamic assemblies of saturated phospholipids associated with unique lipids sphingolipids and lots of cholesterol.
cell membrane proteins that are NOT embedded in the lipid bilayer; include a network of filaments
cell membrane proteins that are firmly inserted into the lipid bilayer; most are transmembrane
plasma membrane/cell membrane proteins
make up the cytoskeleton and 50% of the cell membrane mass
20% of cell membrane lipids; has polar head and nonpolar tail; stabilizes the membrane
lipids with attached sugar groups that comprise 5% of the plasma membrane
lollipop shaped molecule with a polar head that is charged and hydrophilic; has a non polar tail made of 2 fatty acid chains that are hydrophobic
form fabric of the plasma membrane
1) phospholipids, 2) glycolipids, 3) cholesterol, 4) lipid rafts
doesn't like water
small cell structures that perform specific cell functions
Cell functions that involve protein coated vesicles
endocytosis and transcytoisis
a small, cylindrical cell organelle, seen near the nucleus in the cytoplasm of most eukaryotic cells, that divides in perpendicular fashion during mitosis, the new pair of centrioles moving ahead of the spindle to opposite poles of the cell as the cell divide
a cell organelle containing catalase, peroxidase, and other oxidative enzymes and performing essential metabolic functions, as the decomposition of fatty acids and hydrogen peroxide
types of vesicular transport
exocytosis, endocytosis, transcytosis, and substance trafficking
Gases and Fats do this within a cell; when non-polar lipid soluble substances disperse directly through the phospholipid layer, requiring NO ATP (cell energy)
passive cell processes
simple diffusion, carrier mediated facilitated diffusion, channel mediated facilitated diffusion, osmosis
comprised of microtubules, microfilaments and intermediate filaments
outside is studded with ribosomes; area of protein synthesis within the cell
control center of the cell
channel mediated diffusion
Facilitated diffusion that involves channels that do not change shape. Good for water.
types of channel mediated diffusion
leaky and gated
the ability of a solution to make a cell shrink or swell
when a solution has the same solute concentration as that of the cytosol
Secondary Active Transport
a hitchhiking type of cellular transport that depends on an ion gradient created by a primary active transport; requires ATP but only for the primary active transport
a solution has a greater solute concentration than that of the cytosol; cells lose water by osmosis and shrink (crenation)
a system of organelles that work together maintly to produce, degrade, store, and export biological molecules, and degrade potentially harmful substances.
thinnest elements of the cytoskeleton that are semiflexible strands of protein actin
functions of lysosomes
break down bone to release calcium ions into the blood, digest particles taken in by endocytosis (bacteria, viruses and toxins), degrade worn out organelles, perform metabolic functions such as glycogen break down and release, break down useless tissues (webs between fetal digits and uterine lining during menstruation)
microtubule organizing center with a 9x3 array.
fingerlike extensions of the plasma membrane that project from an exposed cell surface
found on the surface of absorptive cells such as intestinal and kidney tubule cells
period from cell formation to cell division; not a part of cell division or replication
subphases of interphase
G1, S, G2
function of mRNA
carries transcript information
cellular adhesion molecule that provides temporary binding sites that guide cell migration and other cell-cell interactions
prevent fluids and most molecules from moving between cells
In what tissue are desmosomes found?
skeletal muscle, ligaments and tendons
In what tissue are tight junctions found?
In what tissue are gap junctions found?
heart muscle, nervous tissue, and some smooth digestive muscle
types of membrane transport
passive and active
passive membrane transport
does not require ATP
Fats and gases diffuse this way
What determines whether or not a substance can passively permeate a membrane?
lipid solubility of the substance, channels of appropriate size, and carrier proteins
transmembrane integral proteins transport specific polar molecules (e.g., sugars and amino acids)
transport certain lipophobic molecules (glucose, ions or amino acids)
types of facilitated diffusion
channels and carrier proteins
types of facilitated diffusion using channel proteins
leakage and gated
Leakage channels are always_____________.
Gated channels are controlled by___________ and _____________.
chemical, electric signals
Aquaporins transport other things other than water.
Required by active transport
carrier proteins (solute pumps)
moves solutes against a concentration gradient
secondary active transport
depends on an ion gradient created by primary active transport
often receptor mediated, therefore very selective
pseudopods engulf solids and bring them into the cell's interior
Macrophages and some white blood cells participate in _________________.
Occurs in nutrient absorption in the small intestine.
receptor mediated endocytosis
clathrin coated pits provide main route for endocytosis and transcytosis
uptake of enzymes, low density lipoproteins, iron and insulin
occur with receptor mediated endocytosis
Roles of cell adhesion molecules
anchor cells to extracellular matrix or to each other, assist in movement of cells past one another, CAMs of blood vessel lining attract white blood cells to injured or infected areas, stimulate synthesis or degradation of adhesive membrane junctions, transmit intracellular signals to direct cell migration, proliferation, and specialization.
cell to environment interactions
involves glycoproteins and proteins of the glycocalyx
Roles of membrane receptors
contact signaling (touching and recognition of cells), chemical signaling (interaction between receptors and ligands), G protein linked receptors (ligand binding activates a G protein, affecting an ion channel or enzyme or causing the release of an internal second messenger
comprised of cytosol, cytoplasmic organelles and inclusions
components of cytosol
water with solutes such as protein, salts, sugars, etc.
granules of glycogen or pigments (melanin), lipid droplets, vacuoles, and crystals
cytoskeleton, centrioles, and ribosomes
mitochondria, peroxisomes, lysosomes, endoplasmic reticulum, Golgi apparatus
interconnected tubes and parallel membranes enclosing cisternae, continuous with nuclear membrane/envelope
studded with ribosomes, manufactures all secreted proteins, synthesizes membrane integral proteins and phospholipids
tubules arranged in a looping network, enzyme functions
synthesis of steroid based hormones
In skeletal and cardiac muscle cells, smooth ER...
storage and release of calcium
In liver cells, smooth ER...
metabolizes lipids and cholesterol, breakdown of glycogen
In kidney cells, smooth ER...
detoxifies drugs, pesticides and carcinogens
In intestinal cells, smooth ER...
absorbs, synthesizes, and transports fats
modifies, concentrates, and packages proteins and lipids
destruction of cells
highly reactive chemicals with unpaired electrons
involved in cell motility, change in shape, endocytosis and exocytosis
tough, insoluble ropelike protein fibers
resists pulilng forces on the cell and attaches to desmosomes
dynamic hollow tubes, most of which radiate from centrosome
determine the overall shape of cell and distribution of organelles
threadlike strands of DNA that are arranged in fundamental units called nuleosomes
ATP powered protein complexes that function in motility
cell center near the nucleus organizes the mitotic spindle
Red blood cells are a) anucleate or b) uninucleate?
Most cells are a) anucleate or b) uninucleate?
cells with more than one nucleus (multinucleate)
skeletal muscles cells, bone destruction cells, and certain liver cells
a double membrane barrier containing pores that maintains the shape of the nucleus
nuclear envelope/nuclear membrane
involved in rRNA synthesis and ribosome subunit assembly
regulate transport of large molecules into and out of nucleus
gap phase in cells that permanently stop dividing
second subphase of interphase that is DNA replication
third subphase of interphase that is characterized by the preparation for division
types of G0 cells
nerve, cartilage, heart
90% of a cell's life is spent in this phase
DNA helices begin unwinding from the nucleosomes, helicase untwists the double helix and exposes the complementary chains, the Y shaped site of replication is the replication fork, each nucleotide strand serves as a template for building a new complementary strand
Does DNA polymerase work in one direction or two directions during DNA replication?
splices together short segments of a discontinuous DNA strand during replication
Four phases of mitosis in order
prophase, metaphase, anaphase, and telophase
essential for growth and repair of cells
mitosis (cell division)
division of cytoplasm by cleavage furrow
2 DNA molecules formed from the original strand
Lagging strand works toward or away from the fork in helicase?
unwinds the double helix and exposes bases of DNA
amino acids the comprise DNA
adenine, cytosine, thymine, guanine
chromosomes become visible, each with two chromatids joined at a centromere
mitotic spindles and asters form
centrosomes spearate and migrate toward opposite poles
second phase of mitosis
centromeres of chromosomes align at the equator
plane midway between the poles
shortest phase of mitosis
when centromeres of chromosomes split simultaneously, and each chromatid now becomes a chromosome
"Go signals" of cell division
critical volume of cell when area of membrane is inadequate for exchange, 2) chemicals
Cdks (cylin-dependent kinases)
a go signal for control of cell division
Cytokinesis begins at which phase of mitosis?
A ring of actin microfilaments contract to form a cleavage furrow on a cell, pinching apart two daughter cells.
The phase during which chromosomes stop moving
During telophase these reappear and these disappear.
three main types of RNA
mRNA, rRNA, and tRNA
What is the master blueprint for protein synthesis?
segment of DNA with blueprint for one polypeptide (protein)
triplets of nucleotide bases form
a genetic library
Specifies coding for an amino acid
carries instructions for building a polypeptide, from gene in DNA to ribosomes in cytoplasm
structural component of ribosomes that, along with tRNA, helps translate message from mRNA
binds to amino acids and pairs with bases of codons of mRNA at ribosome to begin process of protein synthesis
only type of RNA in nucleus
site of both tRNA and mRNA
Steps of protein synthesis
transcription and translation
transfers DNA gene base sequence to a complementary base sequence of an mRNA (it transcribes)
an enzyme that oversees synthesis of mRNA andunwinds the DNA template
loosens histones from DNA in area to be transcribed, binds to promoter, mediates the binding of RNA polymerase to promoter
a DNA sequence specifying start site of gene to be transcribed in transcription
making a partial copy of DNA
making an entire copy of DNA
converts base sequence of nucleic acids into the amino acid sequence of proteins
a complementary three base sequence on mRNA
translation involves what types of RNA?
all of them
anticodon of a tRNA binds to its complementary codon and adds its amino acid to the forming protein chain
intron regions of DNA code
signal recognition particle SRP
found in rough ER; binds with mRNA-ribosome complex during protein synthesis
it tags damaged or unneeded soluble proteins in cytosol
prevents protein coding RNA from being translated
small RNAs that interfere with mRNAs made by certain exons
folded RNAs that act as switches regulating protein synthesis in response to environmental conditions
all cells of the body contain the same DNA but are not_______________.
development of specific and distinctive features in cells
rapid cell death
____________ ___________ in the embryo channel cells into specific delopmental pathways by turning some genes off.
wear and tear theory of cells
little chemical insults and free radicals have cumulative effects
cessation of mitosis and cell again are programmed into genes.
may determine the number of times a cell can divide
strings of nucleotides on the ends of chromosomes